I was looking for a wedding dress that was really different and unique, and I wanted one with sleeves, but not the cheesy poofy Victorian looking ones with the finger cuffs on them or whatever. All the dresses I saw in the shops looked the same. I ended up finding the most beautiful dress, brand new, never been worn, and handmade in India on craigs list. I had to drive a good ways to try it on, but it fit perfectly and cost half as much as I was planning to spend.
Just thought I would mention that, I know many of those listed on sites like ebay and craigs list have already been altered and/or worn, but you might have some luck finding something perfect like I did!